Protective system and device

ABSTRACT

A shutoff device for actuating an electric switch means to open an electric circuit used in a protective system which includes a heat sensory device which causes the shutoff device to operate the switch means upon the occurrence of a fire in a predetermined area.

United States Patent [56] References Cited UNITED STATES PATENTS J. 'r. Milligan [72] Inventor 2700 Mark Drive, Mesquite, Tex. 75149 337/411 (X) 337/411 (X) 200/172 (A) ML "M n "m "enr m eIH C hae S kf M e mmo b LSHMO 55999 66554 H9999 lflHHH 848 4 74870 82292 00806 08976 3J 33222 n %9 11 m7 13 9 1 98 7FA o. d N m n l mm AF? 11.] 25 224 [.11

y n n a a m W .IHO GM M mnn a ai -l e nwm m a e g d i m .l r m a m 6 mm& Mm a W d X& m P W md a mm .m mflm e r t r PmA fi 1 26 23. 0 1 uwmumm wfimm m 3 11 54 m o u w m m V n n "2 E m M] D m m I. u u n m m m m m m I Mm N u .1 n u "I m u n n 5 m m m Y m m sw m m M W m m b2 I m m n 3 m 9. L U 1 mm C G 01 0 H R 3 t k P7 U .m F l l 1 l 4 2 I. 0 5 5 5 5 l l l 1 ABSTRACT: A shutoff device for actuating an electric switch means to open an electric circuit used in a protective system which includes a heat sensory device which causes the shutofi' device to operate the switch means upon the occurrence of a PATENTEI] was] um 3,602,865

sum 2 BF 3 INVENTOR.

J T Mil Ii gon AT T 'ORNE Y PROTECTIVE SYSTEM AND DEVICE This invention relates to protective systems and to a shutoff device usable in such protective systems and more particularly to a protective system for disconnecting electrically operable devices from an electric input circuit and to the combination of'such protective system and a fire extinguishing apparatus.

' An object of this invention is to provide a new and improved shutoff device for disconnecting electrically operable devices from an electric input circuit.

Another object is to provide a shutoff device which is operable by a temperature responsive device, such as a fusible link.

Still another object I is to provide an automatic shutoff device for operating a switch means to open an electric circuit upon the occurrence of a fire.

A further object is to provide a shutoff device of the type described for operating a switch means which has means for causing rapid opening of a switch contact when an operator lever of such switch means is moved a predetermined distance. 7 e

A still further object is to provide a shutoff device having an actuator lever biased for movement in a direction to move such operator lever of a switch means to open position, a latch means for holding the actuator lever against such movement, and a means biasing the latch towards its inoperative position.

Another object is to provide a shutoff device of the type described wherein the actuator lever upon being unlatched, exerts a sudden force on the operator lever greater than the force'exerted by the spring biasing it.

Still another object is to provide a protective system for disconnecting electrically operable devices such as motors, heating elements and the like located in an area protected by a fire extinguishing apparatus wherein both the fire extinguishing apparatusand the protective system are simultaneously placed in operation upon the occurrence of a fire in the protected area. Still another object is to provide a latch device which, when the actuator lever has moved to its operative position opening the operator lever, prevents the operator lever from being moved to its closed position until a heat sensor device is again properly connected thereto.

A further object is to provide a shutoff device operable simultaneously with a fire extinguisher apparatus for causing simultaneous operation of the fire extinguishing apparatus and the disconnection of electrically operable devices from an electric input circuit upon the occurrence of a fire at a preselected location.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description simultaneous operation of the fire extinguisher apparatus;

FIG. 2 is a schematic illustration of the electric circuit of the apparatus illustrated in FIG. 1;

FIG. 3 is a perspective view of an electric shutoff device embodying the invention, with some parts broken away and with a cover plate separated from the housing thereof;

FIG. 4 is an exploded perspective view of a latch assembly of theshutoff device;

FIG. 5 is an enlarged fragmentary partly sectional view showing the shutoff device in its inoperative position;

FIG. 6 is a fragmentary sectional view taken on line 66 of FIG. 5; i

FIG .v 7 is an enlarged sectional view taken on line 7-7 of FIG. 9.; FIG. 8 is a view similar to FIG. 5 showing the shutoff device in its operative position; and, I

Fl 9 is a sectional view taken on line 9-9 of FIG. 8.

Referring now particularly to FIGS. 1 and 2 of the drawings, the electric shutoff or protective apparatus 10 embodying the invention is shown installed to shutoff the operation of the electric motor 11 of the blower or exhaust fan 12 of an air exhaust apparatus 13 which is disposed over a cooking apparatus 15. The cooking apparatus may have a plurality of kettles 16 in which cooking liquids such as oils are heated by means of heating means or element 17. A fire extinguishing apparatus 18 is generally provided for extinguishing fires in the cooking apparatus or in the air exhaust apparatus. The fire extinguishing apparatus may be of the type illustrated and described in the U.S. Pat. No. 3,407,879, issued Oct. 29, 1968. to I-Iarrel W. ORear which includes a main supply pipe or conduit 19, to which a dry powder fire extinguishing chemical is delivered by an inert gas under pressure from a suitable source. This mixture of chemical and gas is delivered from the main pipe by means of a suitable connector fitting 21 and pipes 23a, 23b and 230, to discharge nozzles 24a, 24b and 240, respectively, which spray the mixture upwardly into the three exhaust ducts 25a, 25b and 25c, respectively, of the exhaust apparatus which open at their lower ends to. the hood 26 and which communicate at their upper ends with the end of an exhaust duct 27 of the apparatus.

The exhaust fan 12 moves air from the exhaust duct 27 into the exhaust pipe 28 which opens to the exterior of the building in which the cooking apparatus is located.

The fire extinguishing apparatus 18 also directs the mixture of gas and fire extinguishing chemical over the cooking apparatus 15 and its kettles 16 by means of a plurality of discharge nozzles 33a, 33b and 330 which are connected to the connector fitting 21 by means of conduits 34a, 34b and 340, respectively, a connector fitting 35 and a conduit 36.

The actuator system for causing operation of the fire extinguishing apparatus when a fire occurs at the cooking apparatus or in the air exhaust apparatus may include a heat sensing device, such as a fusible link 38 located in proximity to the hood 26 and cooking apparatus, as for example in the lower end portion of the exhaust duct 27, which will cause an appropriate valve 28 to open to permit the inert gas under pressure to flow from a tank 29 into a tank 30 and force, the dry chemical from the tank 30 into the main conduit 19 and thence through the discharge nozzles up into the exhaust ducts 25 of the air exhaust apparatus and also down onto the cooking apparatus itself to extinguish fires either in the air exhaust apparatus or in the cooking apparatus.

The heating means of the kettles are represented as a single element 17 in FIG. 2 although it will be appreciated that such heating element may have four different sections in the. apparatus illustrated herein, each of which heat the contents of one of the kettles.

The operation of the electrical shutoff or protective apparatus is preferably also controlled by the same sensor, i.e., the fusible link 38 of the fire extinguishing apparatus so that the electric current to the blower motor 11 and the heating element is cut off at the same time the fire extinguishing apparatus is rendered operative. One end of the link 38 is "con: nected to a fixed structure, such as one of the walls of the exhaust duct 27, by a suitable bolt or fastener 41 and a cable 420 and to its other end is connected a flexible member or cable 43a. The cable extends outwardly of the exhaust duct 27 through a 44 connected to a wall thereof into a cable junction box 44a to a connector clamp 44b to which are connected the cables 43 and 42. The cable 43 extends from the box through a pipe 44C over a direction changing pulley 45 rotatably mounted in a connector fitting 46 connected to the outer end of the conduit 44, and downwardly through a conduit 48 into the housing 49 of the shutoff device 50 of the protective apparatus.

The second cable 52 extends through a pipe 42, a direction changing pulley 53a in a connector fitting 53b and a conduit 54 connected thereto to the control lever 55 of the normally closed valve 28 of the fire extinguishing apparatus which causes inert gas under pressure to be introduced into the container 30 of the fire extinguishing dry chemical to force it from the container into the pipe 19 and thence to the various discharge noales of the fire extinguishing apparatus. The electrical shutoff device 50 of the protective apparatus includes a switch means 60, such as a simple two pole mechanically or manually operable switch which operates only on the application of a mechanical or manual force thereto or a circuit breaker which is not only movable mechanically or manually between its open and closed positions, but which also opens automatically in the event that excessive current loads are present in the circuits controlled thereby. For example, the switch means 60 may be a circuit breaker commercially available from Cutler Hammer Company of Milwaukee, Wis., CH 270 Circuit Breaker.

The switch means may have a housing 62 which rests on the bottom wall 63 of the housing 49 of the shutoff device. The housing 62 preferably abuts the sidewall 64 of the housing 49 and may be rigidly secured thereto by screws 65 which extend through suitable apertures in the sidewall 64 into threaded bores of the housing 62. Similar screws may extend through suitable apertures in the bottom wall 63 into threaded downwardly opening bores of the housing 62. The switch housing 62 may similarly be secured by similar screws to the back wall 66 of the housing 49.

The circuit breaker may have two contacts 71 and 72 movable between their closed and open positions by a pair of pivoted levers 73 and 74 which extend outwardly of the front wall of the switch housing 62 through suitable apertures 75 and 76 thereof and which are connected at their outer ends by a connector bar 77 and screws 77a.

Each of the levers 72 and 74 are biased and held in either their closed positions illustrated in FIGS. 2 and 5 wherein they hold their contacts 71 and 72 in their operative or closed positions engaging the stationary contacts 78 and 79, respectively, or in their lower open positions illustrated in FIG. 8 wherein they hold thecontacts in their upper or open positions and in engagement with the stops 84 and 85, respectively, by the springs 81 and 82, respectively.

It will be apparent that the springs 81 and 82 once the levers 73.and 74 have moved past a critical position wherein the lines between the locations of connections of the springs with the levers extends above their pivot axes 87 and 88, FIG. 2, the springs will move the levers upwardly, and that as the levers are moved in the opposite direction about their pivot axes and the lines between the points of connection of the springs with the levers move below their pivot points 87 and 88, the springs tend to move the levers further downwardly and with a snap action. it will thus be apparent that if the levers are pivoted a very short distance from their closed positions, the springs will move the levers to their fully open positions and hold them there. Similarly as the levers are moved from their openpositions past a critical level, the springs will be effective to snap or move them to their fully closed positions.

The above description of the switch means is illustrative only and various snap action mechanisms may be used for this purpose. If such switch means is of the circuit breaker type, additional means are provided which are responsive to overload currents to release or move the levers and their contacts from their closed positions illustrated in FIG. 2 to their open positions.

The levers 73 and 74 are movable to their lower positions, FIG. 8, wherein the contacts 71 and 72 are in their open positions, by an actuator mechanism 90 which includes a mount plate 91 rigidly secured to the other sidewall 92 of the housing 49 by means of screws 93 which extend through suitable apertures 94 in the mount plate 91 into suitable thread bores in the sidewall 92. Alternatively, of course, bolts could be used for this purpose.

A latch 95 is pivotally secured to the mount plate 91 and the sidewall 92 by a screw 96 which extends through an aperture 960 of the latch, a spacer 97. a washer 98, an aperture 99 of the mount plate, a suitable aperture 101 of the sidewall 92 and a nut 102.

The latch is pivoted in a counterclockwise direction about its axis of pivotal movement provided by the screw 96 by a coil spring 103 whose lower hooked end 104 extends about a screw 105 threaded in a suitable aperture in the housing sidewall 92 and whose upper hooked end 106 extends about a tubular pin 108 rigidly secured to the latch 95 by a screw 109 which extends through a suitable aperture in the latch into the internally threaded pin. The latch is held in its normal latching or operative positions against the force exerted thereon by the spring 103, when the fusible link 38 is intact, by the cable 43 which extends transversely through suitable diametric apertures in the tubular pin 108 and a second tubular pin 110 secured to the latch by a screw 111 which extends through a suitable aperture in the latch into the internally threaded pin 110.

The lower end portion of the cable is rigidly secured in any suitable adjusted positions to the pins, and therefore to the latch 95, by means of screws 1 14 and 115, respectively, which are threaded in the outer ends of the tubular pins 108 and 110, respectively, so that the cable is frictionally engaged and held between the inner ends of the pairs of screws extending into opposite ends of the pins.

When the latch is in its operative position, illustrated in FIG. 6, the side surface 118 of its reduced stop end portion 119 engages the edge stop surface 120 of a lug or tooth 121 of an actuator arm 122 to hold the actuator arm against counterclockwise pivotal movement, FIGS. 5 and 8, about pivot pin 124.

The pin 124 extends through aligned apertures 123 and 1240 in the actuator arm 122 and the perpendicular bracket 126 of the mount plate 91. The actuator arm is biased toward the bracket by a spring 127 disposed about the pin 124 whose outer end bears against the bracket and whose inner end bears against a washer 128 which is held against rearward movement on the pin by a cotter key 129 which extends through an aperture 130 in the rear end of the pin. Rearward movement of the pin is limited by a washer 133 which bears against the outer surface of the actuator arm and is held against forward movement on the pin by a cotter key 134 which extends through an aperture 135 in the front end of the pin 124.

The actuator arm 122 has an angularly outwardly extending flange provided with a vertical elongate slot 141 through which extends an actuator rod or lever 142. The lever is mounted for limited pivotal movement on the sidewall 64 of the housing 49 since it extends through an aperture 144 of the sidewall 64 which is of somewhat greater diameter than the lever. A pair of nuts 146 and 147 threaded on the lever on opposite sides of the housing wall 64 limit longitudinal movement of the lever relative to the wall.

The end of the actuator lever remote from the wall is biased downwardly by a spring 148 whose top hooked end portion 149 extends through a suitable aperture 150 in the end of the lever and whose lower hooked end portion 151 extends through an aperture 153 in the housing sidewall 92. Since the lever engages the upwardly facing stop shoulder or surface 155 of the flange 140 defining the lower end of the slot 141, the spring 148 biases the actuator arm in a counterclockwise direction, FIGS. 5 and 8, about the axis of the pivot pin 124.

When the actuator arm is in its operative position illustrated in FIG. 5, it is held against counterclockwise pivotal movemerit about the pivot pin 124 due to the engagement of its stop portion 121 with a stop end portion 119 of the latch 95. As a result, the actuator lever is then also held against pivotal movementin a clockwise direction about an axis at the location of its engagement with the housing wall 64 so that the levers 73 and 74 raised to their upper closed positions wherein the switch contacts 71 and 72 are held in their closed positions. Since the location of engagement of the actuator lever with one or both of the operator levers 73 and 74 is close to its axis of pivotal movement or fulcrum while the spring 148 exerts a downward force on the actuator lever at a location remote from such fulcrum, the force the actuator lever will exert on the levers 73 and 74 is two or three times the force which is exerted on the end of the actuator lever by the spring 148 due to the mechanical advantage thus obtained.

If the link 38 now fails, as, for example, if the temperature at its location rises above the temperature at which it melts, the spring 103 will pivot the latch 95 in a clockwise direction, FIG. 6, moving its stop end portion up above the lug 121 of the actuator arm thus freeing the actuator arm for pivotal movement in a counterclockwise direction. Due to the sudden release of the actuator arm, the actuator lever is moved suddenly downwardly, exerting a relatively large force on one or both the levers 73 and 74 thus causing the levers to move the contacts 71 and 72 to their open positions. The actuator lever, of course, needs to move the switch levers a very short distance downwardlyagainst the resistance of their biasing means, such as the springs 81 and 82, and such biasing means themselves, will complete the movement of the levers to their lowermost fully closed positions. The apparatus is now held in its closed position by the cables 42 and 43 even though its operator lever 55 is biased towards its open position by a spring 210. The operator may now place the cooking apparatus in operation by closing the manual switch 180 which may be located'at any convenient location and the exhaust fan by closing the switch 186.

If due to the occurrence of a fire, either in the kettles, in the hood and exhaust ducts, or in any of the filters (not shown) which may be mounted in the hood 26, the temperature at the location of the usable link 38 rises,'the link 38 will fail. As soon as the link fails, the spring 210 is effective to move the operator lever 55 of the valve 28 to open the valve and inert gas flows from the tank 29 into the tank 30 and forces the dry chemical fire extinguishing chemical through the main pipe 19 to the nozzles so that a mixture or spray of the dry fire extinguishing chemical and the inert gas is then discharged through the discharge nozzles onto the cooking apparatus 15 and into the exhaust apparatus 13.

Simultaneously, the spring 103 moves the latch 95 in a counterclockwise manner so that its stop end portion 119 moves out of engagement with the lug 121 of the actuator arm. Once the latch arm moves out of engagement with the mg 121 of the actuator arm, the spring 148 moves the actuator lever 142 downwardly, since the actuator arm is now free to pivot in a counterclockwise direction from the position illustrated in FIG. 5 to the position illustrated in FIG. 8. As a result, the actuator lever is suddenly pivoted downwardly in a clockwise direction about an axis at the location of the wall 64. As the actuator lever is suddenly pivoted downwardly, it forces the operator levers 73 and 74 downwardly past the critical, point at which the biasing means of the levers, such as the springs 81 and 82, stop resisting such downward movement and start assisting it so that the actuator lever need move only a very' short distance to cause opening of the switch contacts 71 and 72. Asa result, the fan motor 11 and the heating elements or means 17 of the cooking apparatus are disconnected from the electric input circuit. The advantages in stopping the energization of the fan motor and the heating elements are quite obvious since it is desirable that the cooking apparatus cool off as rapidly as possible and that circulation of air-through the exhaust apparatus be stopped as soon as possible to minimize the spread of the fire as well as to not sustain the fire by drawing fresh oxygen laden air thereto.

Once the fire is extinguished, the operator cannot again connect either the fan or the heating elements to the electric input circuit since the actuator rod is now held in its lower position illustrated in FIG. 8 preventing movement of the switch lever arm 73 and 74 to their fully closed positions. The

link 38 must then be replaced, it being apparent that the exhaust duct is provided with an access door for this purpose at the location of the fusible link. While a particular cooking apparatus and exhaust apparatus have been illustrated and described to facilitate the description of the mode of operation of the protective system 10 embodying the invention, it will be apparent that the shutoff device may be used in any suitable installation where it is desired to shut off the electric power to disconnect electrical devices, such as motor, heating elements and the like from an electric input circuit upon the occurrence of some predetermined condition such as a fire, a rise in temperature or the like.

It will be apparent that if the cooking apparatus extended over a large area, a number of fusible links could be connected in series at spaced locations to constitute sections of a flexible member or cable, such as the one formed by the cables 42a and 43a and the fusible link 38, so that a fire at any one of several spaced locations would cause failure of one or more such links and the shutting-off of the electric current from the electrically energized devices in such area.

It will now be seen that the shutoff or protective system may be used in combination with a fire extinguishing apparatus and that both the shutoff device and the fire extinguishing apparatus may be simultaneously operated upon the occurrence of a fire in an area protected by such fire extinguishing apparatus.

What is claimed and desired to be secured by Letters Patent 1. In combination: a switch means having an operator lever movable between open and closed positions; and a shutoff device for operating said switch means, said shutoff device including: an actuator lever mounted at one end for pivotal movement between an inoperative position and an operative position, said actuator lever extending past said operator lever of said switch means for engaging said operator lever and moving it from its closed toward its open position upon move ment of said actuator lever in one direction from said inoperative to said operative position; means connected to the other end of said actuator lever biasing said actuator lever for move ment in said one direction; latch means for releasably holding said actuator lever in said inoperative position and against movement in said one direction when said latch means is in latching position; means for holding said latch means in said latching position; and means biasing said latch means for movement from its latching position in a direction to release said actuator lever for movement in said one direction. 7

2. The shutoff device of claim 1, wherein said latch means includes a movable actuator arm, said actuator arm having stop means engageable with said actuator lever for holding said actuator lever in its inoperative position; and a latch mounted for movement between a latching position and a released position, said latch and said actuator arm having coengageable means for holding said actuator arm in position holding said actuator lever in its inoperative position when said latch is in said latching position; means biasing said latch for movement from said latching position to said released position, said latch having means for connecting a flexible member thereto whereby the latch may be held by said flexible member in its latched position against the force exerted thereon by said biasing means.

3. The shutoff device of claim 2, wherein said actuator arm is pivotally movable about an axis perpendicular to the axis of pivotal movement of said actuator lever.

4. A shut off device for opening an electric circuit including: a housing; a switch means mounted in said housing, said switch means having an operator lever movable between an upper closed position and a lower open position; an actuator lever in said housing extending above said operator lever and pivotally mounted at one end for downward movement for engaging said operator lever and moving it from its closed toward its open position upon downward pivotal movement of said actuator lever; means in said housing connected to the other end of said actuator lever biasing said actuator lever downwardly; latch means mounted in said housing for releasably holding said actuator lever against downward movement when said latch means is in latching position; means connectable to said latch means and extending outwardly of said housing for holding said latch means in said latching position; and means biasing said latch means for movement from its latching position in a direction to release said actuator lever for downward movement.

5. The shutoff device of claim 4, wherein said latch means includes an actuator arm movably mounted in said housing for movement between a first position wherein said actuator arm holds said actuator lever against downward movement and a second position wherein said actuator lever is in a lower position; and a latch mounted for movement between a latching position and a release position, said latch and said actuator arm having coengageable means for holding said actuator arm in position holding said actuator lever in its upper position when said latch is in said latching position; means biasing said latch for movement from said latching position to said release position, said flexible member being connected to said latch means and extending upwardly therefrom and said housing whereby said latch may be held by said flexible member in its latched position against the force exerted thereon by said biasing means.

6. The shutoff device of claim 5 wherein said housing includes spaced vertical front and second sidewalls and extending toward said second wall, said latch means beingmounted on the said second sidewall, said actuator lever being engageable intermediate its ends with said operator lever.

7. The shutoff device of claim 6, wherein said switch means includes means for biasing said operator lever toward its lower position when said lever is moved a predetermined distance from upper toward said lower position past an intermediate position, said actuator lever when released for movement moving said operator lever past said intermediate position. 

1. In combination: a switch means having an operator lever movable between open and closed positions; and a shutoff device for operating said switch means, said shutoff device including: an actuator lever mounted at one end for pivotal movement between an inoperative position and an operative position, said actuator lever extending past said operator lever of said switch means for engaging said operator lever and moving it from its closed toward its open position upon movement of said actuator lever in one direction from said inoperative to said operative position; means connected to the other end of said actuator lever biasing said actuator lever for movement in said one direction; latch means for releasably holding said actuator lever in said inoperative position and against movement in said one direCtion when said latch means is in latching position; means for holding said latch means in said latching position; and means biasing said latch means for movement from its latching position in a direction to release said actuator lever for movement in said one direction.
 2. The shutoff device of claim 1, wherein said latch means includes a movable actuator arm, said actuator arm having stop means engageable with said actuator lever for holding said actuator lever in its inoperative position; and a latch mounted for movement between a latching position and a released position, said latch and said actuator arm having coengageable means for holding said actuator arm in position holding said actuator lever in its inoperative position when said latch is in said latching position; means biasing said latch for movement from said latching position to said released position, said latch having means for connecting a flexible member thereto whereby the latch may be held by said flexible member in its latched position against the force exerted thereon by said biasing means.
 3. The shutoff device of claim 2, wherein said actuator arm is pivotally movable about an axis perpendicular to the axis of pivotal movement of said actuator lever.
 4. A shut off device for opening an electric circuit including: a housing; a switch means mounted in said housing, said switch means having an operator lever movable between an upper closed position and a lower open position; an actuator lever in said housing extending above said operator lever and pivotally mounted at one end for downward movement for engaging said operator lever and moving it from its closed toward its open position upon downward pivotal movement of said actuator lever; means in said housing connected to the other end of said actuator lever biasing said actuator lever downwardly; latch means mounted in said housing for releasably holding said actuator lever against downward movement when said latch means is in latching position; means connectable to said latch means and extending outwardly of said housing for holding said latch means in said latching position; and means biasing said latch means for movement from its latching position in a direction to release said actuator lever for downward movement.
 5. The shutoff device of claim 4, wherein said latch means includes an actuator arm movably mounted in said housing for movement between a first position wherein said actuator arm holds said actuator lever against downward movement and a second position wherein said actuator lever is in a lower position; and a latch mounted for movement between a latching position and a release position, said latch and said actuator arm having coengageable means for holding said actuator arm in position holding said actuator lever in its upper position when said latch is in said latching position; means biasing said latch for movement from said latching position to said release position, said flexible member being connected to said latch means and extending upwardly therefrom and said housing whereby said latch may be held by said flexible member in its latched position against the force exerted thereon by said biasing means.
 6. The shutoff device of claim 5 wherein said housing includes spaced vertical front and second sidewalls and extending toward said second wall, said latch means being mounted on the said second sidewall, said actuator lever being engageable intermediate its ends with said operator lever.
 7. The shutoff device of claim 6, wherein said switch means includes means for biasing said operator lever toward its lower position when said lever is moved a predetermined distance from upper toward said lower position past an intermediate position, said actuator lever when released for movement moving said operator lever past said intermediate position. 